Dynamic radio receiver and amplifier



DYNAMIC RADIO RECEIVER AND AMPLIFIER Filed May '18. 1926 2 Sheets-Sheet l ATTORNEYS WITN SE5" I DINVENTORI Q Q Georye Zald Feb. 11, 1930. I WALD 1,747,137

DYNAMIC RADIO RECEIVER AND AMPLIFIER Filed May 18, 1926 2 Sheets-Sheet 2 5o VOLTS 45 v -4o $1.5. ARP'IATURE 3O VOLTS 20 E B I5 I .0

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WITN SE5 INVENTOR 4 g 060 112M BY ga /9W ATTORNEYS Patented Feb. 11, 1930 PATENT OFFICE GEORGE WALD, F ANNISTON, ALABAMA DYNAMIC RADIO RECEIVER AND AMPLIFIER Application filed May 18, 1926. Serial No. 109,942.

This invention relates to a dynamic radio receiver and amplifier.

An object of the invention is to provide a simple and efficient receiving circuit in conjunction with an amplifier which does away with the use of a battery and vacuum tubes. A further object is to provide an amplifier in which a much greater degree of amplification can be obtained.

The invention is illustrated in the drawings, of which Figure 1 is a diagrammatic view of the general principles of the invention;

Figure 2 is a section through one of the transformer generators employed;

Figure 3 is a diagrammatic view of a complete circuit employing four stages of amplification;

Figure 4: is a section through a radio receiving casing showing in a somewhat diagrammatic manner the apparatus disposed therein.

Figure 5 is a diagram of the characteristic curve of a direct current shunt generator.

Figures 6, 7 8 and '9 show diagrammatic views of means whereby generators may be variously excited.

The form of the invention shown in the drawings is a preferred form, although it is understood that modifications in the construction and arrangement of the materials and in the character of the materials used may be adopted without departing from the spirit of I the invention as set forth in the appended claims.

In its general aspect the invention concerns the use of one or more small generators as transformers, instead of the usual transformers, for the purpose of amplifying radio current. Each generator is provided with two field coils and an armature winding. One of.v

the field coils is separately excited from a common source with the corresponding coils of other generators in the system and the other field coil on each generator is associated in circuit either with the radio tuning circuit or with the armature circuitsof proceding generators in series. If a plurality of generators are used they are all driven by a common motor and mounted on the same shaft therewith preferably. This shaft also is connected to a small generator which feeds the regulated current through the separately excited coils of the transformer generators.

Preferably the transformer generators are bi-polar with the pole covering only a small angle of the armature. Brushes preferably are disposed at right angles to the line between the poles. Suitable condensers and rheostats are used in a manner hereinafter described.

In the preferred form of the invention, the general principle of which I haveillustrated in Figure 1, I employ any standard tuning circuit embodying a coupling coil 10, a variable condenser 11, a crystal detector 12, a fixed condenser 13 and grid leak 14. Instead of the usual transformers to amplify the signals thus received, I employ a generator having an armature 15 and field windings 16 and 17, an armature is connected either to another generator or to headphones or loudline between the field poles. Mounted on the field poles are the coils 16 and 17 above mentioned. By reason of the small angular occupation of the pole there are a few active coils producing voltage and the brushes will short-circuit the absolutely inactive coils in the armature, thus enabling an ordinary direct current generator to do the work and yet avoid voltage rippling, or changes in voltage. I

In Figure 3 I show a circuit including four stages of amplification connected to a tuning circuit on one side and a loud speaker on the other. In this Figure, 26 is an ordinary light socket with plug, 27 is a Dubilier condenser to plug in the tuning circuit on to the light socket and use the light circuit as an aerial, 28 is a tuning coil, 29 a variable condenser, 30

a grid leak, 31 a crystal or other type detector, 32 is a fixed condenser, 33 a motor connected to the light circuit, 34 a shaft connected to a generator 35 in series with rheostat 36. In parallel across the generator 35 are the separately excited coils 17 of the transformer generators used. The coils 16 are shown. The armatures ofthe generators 37, 38, 39 and 40 are connected in series with condensers 41 and in parallel with condensers 42. The last transformer circuit is connected" to a loudspeaker 43 by suitable connection.

In Figure 4 I show the mechanical embodiment of this idea, which includes a box 44, preferably made sound-proof and employing a motor 33, a generator 35 and the transformer generators 37, 38 and 39 mounted on a common shaft 45. The rheostat 36 is shown in series with the armature of the generator 1 35 and in parallel with the separately excited coils 17. The loudspeaker plug 46 is'disposed in the wall of the box and the variable condenser 29 is mounted on a shaft 47 leading to a dial 48 on the outside of the box. The light socket connection 49 to the motor 33 is also outside of the box. Otherwise the apparatus is all disposed within the sound-proof container.

In Figure 5 I show the characteristic curve of a direct current shunt generator and the portion marked AB indicates the portion In re ard to the advanta es of 111 construction, by having the condensers in series with each armature, I cut ofi the direct current flow in any of the amplifying stages. This is important inasmuch as any current outside of the audio currents circulating within these circuits will have a reactive effect to distort the balancing combination of the circuit. Furthermore, sparking at the commutators will be avoided by the use of these condensers. By having a rheostat in series with the separately excited field wind-' ings, changes in the excitation of the field is avoided, so as to make the instrumentselective in accordance with the distance of the transmitting stations. The use of a crystal detector in place of the vacuum tubes does away with the batteries.

In the operation of the device, radio current will be received by the tuning circuit and I show a generator with the this current will be rectified by the detector, whereby the audio current will flow in the field windings 16, causing a variable magnetic flux to be set up in the field in synchronism With the audio current received. This produces a corresponding voltage change across the armatures, as this armature circuit is stopped, for continuous direct currents, by a low pass condenser.

As the detector is of the crystal type the current in'coil 16'is very low. However, as the amplification progresses the armature current changes increase; therefore, the magnitude of the corresponding condensers 42 is also increased.

The main idea is to utilize the unsaturated condition of the direct current generator magnetic circuit to cause high amplification of audio-current by causing the armature to revolve in said magnetic field, the circuit of which armature is to be kept open 'by a low pass condenser in series therewith. Owing to the high audio amplification no radio frequency amplificationis needed. Only one tuningdevice, namely, the condenser 29, is needed, thus requiring only one controlling dial 48 in addition to the rheostat 36.

What I'claim is:

1. A transformer especially adapted for radio which comprises a generator having an armature winding and two field windings, one field winding acting as a primary for signal currents, the armature acting as a secondary, and means for exciting the second field winding from a source of current independent of the signal current. v

2. A radio circuit which includes a plurality of generators, each having an armature winding and two field windings acting as transformers, one of said field windings of each generator acting as a primary for signal currents, the armature of each generator acting as a secondary, and means for exciting the second field winding from a source of current independent of the signal current.

3. A radio apparatus which comprisesa shaft driven by a motor, a plurality of generators, certain of said generators acting as transformers in the radio circuit and having armature windings and two field windings one of said field windings in each generator acting as a primary and the other acting as a control winding, the armature windings acting as secondaries, the control windings being connected in parallel to one of the other generators whereby they may be separately excited.

4. A radio transformer which comprises a generator having an armature winding, a pair of field windings mounted on field poles occupying a very small angular space with respect to the armature brushes of the generator and being disposed at right angles to the axis of the field poles.

5. A radio transformer which comprises a generator having an armature winding, a pair of field windings mounted on field poles occupying a very small angular space with respect to the armature brushes of the generator and being disposed at right angles to the axis of the field poles, one of the field windings acting as a primary and receiving alternating current from a previous generator transformer, and the other field winding being separately excited and acting as a control winding, the armature of the generator acting as a secondary and being connected with the primary winding of the next succeeding transformer.

6. A radio transformer which comprises a generator having an armature winding, a pair of field windings mounted on field poles occupying a very small angular space with respect to the armature brushes of the generator and being disposed at right angles to the axis of the field poles, one of the field windings acting as a primary and receiving alternating current from a previous generator transformer, and the other field winding being separately excited and acting as a control Winding, the armature of the generator acting as a secondary and being connected with the primary winding of the next succeeding transformer, and condensers in parallel and in series with the armature windings.

7. In a signal receiving apparatus of the character described, a direct current generator, a circuit for the armature of the generator capable of transferring pulsating or alternating currents but open to direct currents, a constant field for the generator, and means for influencing said field by signal currents.

8. In a signal receiving apparatus of the character described, a direct current generator, a circuit for the armature of the generator capable of transferring pulsating or alternating currents, but open to direct currents, and means for influencing the voltages developed by the armature by rectified signal currents.

GEORGE WALD. 

